• ½ lb  (225 g) mushrooms
• 1 small onion
• ½ pint (300 ml) water or white vegetable stock
• Salt and pepper
• 1 oz (28 g) butter
• 1 oz (28 g) flour
• ¾  pint (400 ml) milk
• 1 egg yolk

Method:

1. Clean the mushrooms and cut up roughly.
2. Peel and chop the onion finely.
3. Put into a pan with the stock or water and seasoning.
4. Bring to the boil and then reduce to a simmer with the pan covered for about 20 minutes until the mushrooms are cooked.
5. Either rub through a sieve or put through a blender to make a smooth pureee.
6. Melt the butter in a pan and add the flour. Blend it well and cook for a minute or two without colouring.
7. Gradually pour in the milk, stirring all the time. Simmer for a few minutes to cook.
8. Pour in the mushroom puree and add the beaten egg yolk.
9. Stir over a low heat to re-heat without boiling..
10. Serve hot.

Serves 4 - Nice if served with croutons of fried bread.